Lori Marino

Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence

The ability to recognize oneself in a mirror is an exceedingly rare capacity in the animal kingdom. To date, only humans and great apes have shown convincing evidence of mirror self-recognition. Two dolphins were exposed to reflective surfaces, and both demonstrated responses consistent with the use of the mirror to investigate marked parts of the body. This ability to use a mirror to inspect parts of the body is a striking example of evolutionary convergence with great apes and humans.

Convergence of Complex Cognitive Abilities in Cetaceans and Primates

What examples of convergence in higher-level complex cognitive characteristics exist in the animal kingdom? In this paper I will provide evidence that convergent intelligence has occurred in two distantly related mammalian taxa. One of these is the order Cetacea (dolphins, whales and porpoises) and the other is our own order Primates, and in particular the suborder anthropoid primates (monkeys, apes, and humans). Despite a deep evolutionary divergence, adaptation to physically dissimilar environments, and very different neuroanatomical organization, some primates and cetaceans show striking convergence in social behavior, artificial ‘language’ comprehension, and self-recognition ability. Taken together, these findings have important implications for understanding the generality and specificity of those processes that underlie cognition in different species and the nature of the evolution of intelligence.

A COMPARISON OF ENCEPHALIZATION BETWEEN ODONTOCETE CETACEANS AND ANTHROPOID PRIMATES

There have been very few studies of brain size and encephalization in cetaceans and essentially none that have made direct quantitative comparisons of cetaceans and another mammalian group using large normative samples. In the present study two different measures of encephalization were calculated and used to rank and compare 21 odontocete species and 60 anthropoid primate species. Comparisons were made both within and between the two groups. Results show that the encephalization level of Homo sapiens is still extraordinary relative to that of nonhuman species. Nevertheless, a subset of delphinid odontocetes are significantly more highly encephalized than the most highly encephalized anthropoid primates and narrow the gap in encephalization between humans and nonhumans substantially. These findings may have implications for comparative models of the relative importance of brain size versus brain organization for the evolution of intelligence.

Planum temporale asymmetries in great apes as revealed by magnetic resonance imaging (MRI).

THE planum temporale (PT), a portion of Wernickes area, is important for linguistic functions in humans and is larger in the left compared to the right hemisphere. In this study, we assessed the presence and size of the PT in a sample of non-human primates including 21 great apes, four lesser apes, 11 Old World monkeys and eight New World monkeys using magnetic resonance imaging. The PT was measured in both the sagittal and coronal planes by use of multiplanar reformatting software. The PT could only be identified in the sample of great apes and not in the remaining non-human primate species. Within the great ape sample, the PT was larger in the left hemisphere than in the right in a statistical majority of the subjects. These results are consistent with the notion that the PT evolved as a definable structure about 15 million years ago and may have arisen as a result for selection for greater cortical folding which in turn led to greater gyrification in larger brains.

What can dolphins tell us about primate evolution

Fifty‐five million years ago, a furry, hoofed mammal about the size of a dog ventured into the shallow brackish remnant of the Tethys Sea and set its descendants on a path that would lead to their complete abandonment of the land. These early ancestors of cetaceans (dolphins, porpoises, and whales) thereafter set on an evolutionary course that is arguably the most unusual of any mammal that ever lived. Primates and cetaceans, because of their adaptation to exclusively different physical environments, have had essentially nothing to do with each other throughout their evolution as distinct orders. In fact, the closest phylogenetic relatives of cetaceans are even‐toed ungulates.

Do Zoos and Aquariums Promote Attitude Change in Visitors? A Critical Evaluation of the American Zoo and Aquarium Study

Modern-day zoos and aquariums market themselves as places of education and conservation. A recent study conducted by the American Zoo and Aquarium Association (AZA) (Falk et al., 2007) is being widely heralded as the first direct evidence that visits to zoos and aquariums produce long-term positive effects on people’s attitudes toward other animals. In this paper, we address whether this conclusion is warranted by analyzing the study’s methodological soundness. We conclude that Falk et al. (2007) contains at least six major threats to methodological validity that undermine the authors’ conclusions. There remains no compelling evidence for the claim that zoos and aquariums promote attitude change, education, or interest in conservation in visitors, although further investigation of this possibility using methodologically sophisticated designs is warranted.

Asymmetries in cerebral width in nonhuman primate brains as revealed by magnetic resonance imaging (MRI).

A comparative study of asymmetries in cerebral width was conducted in a sample of great apes, Old World and New World monkeys. The brains of all subjects were scanned using magnetic resonance imaging (MRI) and the first axial slice above the third ventricle was identified. Measures of cerebral width were taken at distances of 10% and 30% of the length from the occipital and frontal poles. Cerebral widths were measured from the midline to the lateral surface of the brain for each area. The great apes exhibited a right-frontal and left-occipital directional asymmetry in cerebral width. In contrast, no significant mean directional asymmetries were found in either the Old or New World monkeys. The results in the great apes are consistent with previous reports of petalia asymmetries and suggest that the use of MRI is a valid approach to the assessment of neuroanatomical asymmetries in primates.

Relative Volume of the Cerebellum in Dolphins and Comparison with Anthropoid Primates

According to the ‘developmental constraint hypothesis’ of comparative mammalian neuroanatomy, brain growth follows predictable allometric trends. Therefore, brain structures should scale to the entire brain in the same way across mammals. Evidence for a departure from this pattern for cerebellum volume has recently been reported among the anthropoid primates. One of the mammalian groups that has been neglected in tests of the ‘developmental constraint hypothesis’ is the cetaceans (dolphins, whales, and porpoises). Because many cetaceans possess relative brain sizes in the range of primates comparative tests of the ‘developmental constraint hypothesis’ across these two groups could help to delineate the parameters of this hypothesis. In this paper, we compare relative cerebellum volumes in two cetacean species, the bottlenose dolphin (Tursiops truncatus) and the common dolphin (Delphinus delphis), with published data from anthropoid primates. We found that relative cerebellum size is significantly greater in the two dolphin species than in any of the primates, including humans. These results suggest that there is possibly expansion of brain structures independent of strictly allometric processes.

Dolphin-Assisted Therapy: More Flawed Data and More Flawed Conclusions

ABSTRACT Dolphin-Assisted Therapy (DAT) is an increasingly popular choice of treatment for illness and developmental disabilities by providing participants with the opportunity to swim or interact with live captive dolphins. Two reviews of DAT (Marino and Lilienfeld [1998] and Humphries [2003]) concluded that there is no credible scientific evidence for the effectiveness of this intervention. In this paper, we offer an update of the methodological status of DAT by reviewing five peer-reviewed DAT studies published in the last eight years. We found that all five studies were methodologically flawed and plagued by several threats to both internal and construct validity. We conclude that nearly a decade following our initial review, there remains no compelling evidence that DAT is a legitimate therapy or that it affords any more than fleeting improvements in mood.

Construct Validity of Animal-Assisted Therapy and Activities: How Important Is the Animal in AAT?

ABSTRACT Animal-assisted therapy and animal-assisted activities involve a nonhuman animal as a key therapeutic agent in some kind of intervention that may range from highly specified, as in AAT, to more casual, as in AAA. In this review I address the question: How important is the animal in animal therapy? In other words, does the recent literature strongly support the notion that a live animal, as opposed to another novel stimulating component, is specifically necessary for therapeutic success. Two meta-analyses and 28 single empirical studies were reviewed in order to address this issue. I conclude that the effects of AAT and AAA are likely to be moderate and broad at best and that, although improving, the literature has not yet reached an experimentally rigorous enough level to provide a definitive robust conclusion about the effectiveness of these approaches, particularly with regard to the question of whether a live animal is necessary for a therapeutic effect.